Sustainable development is a concept that focuses on meeting the needs of the present generation without compromising the ability of future generations to meet their own needs. It incorporates three key aspects:
1. Economic growth: Ensuring long-term economic stability and growth while maintaining the efficient use of resources.
2. Environmental protection: Preserving biodiversity, ecosystems, and reducing pollution to maintain a healthy planet.
3. Social equity: Addressing social inequalities, providing equal opportunities, and creating access to basic services such as education and healthcare.
Sustainable development aims to strike a balance between economic progress, environmental sustainability, and social well-being to ensure a harmonious coexistence for all.
Assertion (A): The sum of the first fifteen terms of the AP $21, 18, 15, 12, \dots$ is zero.
Reason (R): The sum of the first $n$ terms of an AP with first term $a$ and common difference $d$ is given by: $S_n = \frac{n}{2} \left[ a + (n - 1) d \right].$